Researchers unveil 'comprehensive' test to detect genetic modification in foods
The new method - known as MACRO - is reported to be the first to comprehensively test genetic modifications in foods using a single accurate test.
Writing in the journal Analytical Chemistry, the team behind the new testing method noted that as the abundance of genetically modified (GM or GMO) foods continues to grow, so does the demand for monitoring and labelling them.
"Despite strict regulations, unauthorized GMOs have been occasionally released into the market. There is thus an urgent need for high capacity monitoring of GMOs," wrote the research team - led by Li-Tao Yang from Jiao Tong University, China.
"An ideal solution for GMO monitoring would be a single test that is specific, sensitive, cost-effective, and capable of covering the majority of the GM events," they said. "To date, a wide variety of methodologies have been developed for the monitoring of GM contents, but these fall short of the ideal goal as, generally, they are effective for only a limited number of samples."
By combining two individual tests in to one easy to perform methodology the Chinese team believe they have now created a single test that is able to flag up around 97% of the known commercialised modification - almost twice as many as other tests. Yang and colleagues added that the test can also be easily expanded to include any future genetically modified crops.
"We believe MACRO is the first system that can be applied for effectively monitoring the majority of the commercialised GMOs in a single test."
The researchers developed the MACRO system (a Multiplex Amplification on a Chip with Readout on an Oligo microarray) 'specifically for convenient GMO monitoring' and is made up of a PCR chip for the multiplex amplification of 91 target DNA fragments (18 universal elements, 20 exogenous genes, 45 events, and 8 endogenous reference genes) and an oligo microarray for the readout of the amplified DNA fragments.
The MACRO results of simulated complex samples and blind samples were 100% consistent with expectations and the results of independently performed real-time PCRs, respectively.
The test covers 97.1% of all GMOs that have been commercialised up to 2012 with approximately 100% accuracy - something the team said allows it to be 'suitable for real-world applications'.
Indeed, a comparison between results from the MACRO method and independently performed real-time PCRs showed 100% consistency, said the team.
"Thus, we believe MACRO is the first system that can be applied for effectively monitoring the majority of the commercialised GMOs in a single test."
Yang and colleagues added that while the MACRO system may offer benefits over other testing methods and could easily be applicable for routine GMO monitoring, "there is still room for improvements."
"Though the sensitivity of the current MACRO system is sufficient for routine GMO monitoring, it could be challenging for monitoring samples with low concentration of GM contents, such as less than 200 copies/μL," they said. "However, this challenge can be overcome by a simple DNA preconcentration procedure, which can easily increase the template DNA concentration by 10–100 times and thus increase the sensitivity of MACRO to as low as 20 copies/μL."
"Because of its superior advantages over the existing GMO monitoring methodologies, we strongly believe that the MACRO system will be widely applied for future routine GMO monitoring and UGM inspection," the team concluded.
Source: Analytical Chemistry
Published online ahead of print, doi: 10.1021/ac403630a
"MACRO: A Combined Microchip-PCR and Microarray System for High-Throughput Monitoring of Genetically Modified Organisms"
Authors: Ning Shao, Shi-Meng Jiang, Miao Zhang, et al